I'm BACK! I can run again!!
Ended up taking a week off, then two very very slow runs, this week and today back up to speed again. Still getting the odd niggle, but taking ibuprofen and it's not like it was before where I could barely walk after a run. I missed it so much last week, it's strange how important it has become to me.
nextphase, it is possible to run very very slowly and not be walking, it's a different movement. I think someone said on here once that they were going so slowly they could have probably walked faster but it still counted as they did have two feet off the ground at points! On Monday I was only running at 4.5mph at one point because I've been recovering from a knee injury. 5k in 40 mins with only 9 mins running does sound pretty fast to me. If you were walking briskly at 4mph, that means u were running at over 7 mph to cover that distance. I'd try to slow down to a really gently jog rather than to the walk, even if it is slower than your walking pace.
For those with dodgy knee joints I find it helps to do offroad as well as road running. I have hypermobile knees and so prone to issues, but running offroad is def easier on it. Running on uneven paths or adverse camber also plays mine up.